The rheological behavior of polysaccharides sequential extracted from Polygonatum cyrtonema Hua

The present study investigated the rheological properties of polysaccharides (HBSS, CHSS, DASS, CASS) sequentially extracted from Polygonatum cyrtonema Hua. The monosaccharide, uronic acid, total carbohydrate, protein content of four polysaccharides were analyzed. The total carbohydrate content of PCHPs (HBSS, CHSS, DASS, and CASS) were 78.39, 71.86, 69.99 and 73.73% respectively, containing Rha, Ara, Man, Gal besides uronic acid and protein. The non-Newtonian fluidic nature of PCHPs was affected by the types of polysaccharides, concentration, temperature, pH, types and concentration of salt ions. Specifically, the apparent viscosity of four PCHPs solutions at 1% (w/w) concentration were shown as CHSS > HBSS > CHSS > CASS with increased concentration and shear thinning phenomenon and decreased system temperature. Subsequently, the apparent viscosity of four PCHPs at pH 10 or pH 4 were lower than that at pH 7. The Na+ increased the apparent viscosity of HBSS at increasing concentrations, while, decreased for remaining fractions with increasing Na+ concentration. Moreover, higher Ca2+ concentration was inversely proportional to apparent viscosity of four PCHPs. The oscillatory rheological properties showed that linear viscoelastic region of PCHPs was 1-4% which resulted into viscoelastic material. HBSS, DASS and CASS at 0.1% (w/w) showed more viscous behavior at low frequency and enhanced elastic property with the increasing oscillation frequency.